南澳多端柔性直流输电工程交直流相互影响分析

Analysis on AC/DC Interaction of Nan'ao Multi-terminal Flexible VSC-HVDC Transmission Engineering

为了给南澳多端柔性直流输电工程的调度运行提供指导,对南澳工程的运行特性及交直流相互影响进行了分析。首先介绍了南澳工程概况,分析柔直工程的故障穿越特性,明确主网哪些交流站点发生故障将导致柔直闭锁;其次探讨主网故障对风电场经柔直并网送出的影响,比较了纯直流运行方式与交直流并联方式在故障隔离方面的差异;最后研究了柔直在交直流并联方式运行时,交直流输电通道故障分别对供送电能力的影响。分析结果认为:主网侧交流系统故障可能导致柔直因充电过电压而闭锁,而交流侧故障造成直流电压的波动很小,因而柔性直流具有隔离故障的功能。

In order to provide guidance for dispatching operation of Nan’ao multi-terminal flexible VSC-HVDC transmission engineering,this paper analyzes operation characteristic and AC/DC interaction of the engineering. It firstly introduces general situation of the Nan’ao engineering,analyzes fault ride-through of the engineering and confirms faults of AC station sites that may cause flexible HVDC interlock. Secondly,it discusses affect on wind power sending via flexible HVDC by fault of the main power grid and compares differences of pure DC operation mode and AC/DC parallel connection mode in fault isolation. At last,it studies affects on power supply and transmission capacities by faults of AC and DC power transmis-sion channels under AC/DC parallel connection mode. The analysis results consider that fault of AC system at the main grid side may causeinterlock of the flexible HVDC because of charging overvoltage,while the fault at AC side brings about little fluctuation of DC voltage,which indicates that flexible VSC-HVDC is provided with function of fault isolation.